Not sure you'd need to cut the dash, cut some flat textured plastic sheet to the same size as the front of your stock stereo and cut a hole in that for the screen. Mount the flat panel in the opening vacated by the stereo so that it is flush with the back of the dash trim & you're done.
Not easy, but you could put a screen in there without cutting the dash trim. You just have to lose (or move the stereo).
I'm sure someone who has done this will chime in. I have as yet to do it myself.
If removing the stereo & fabricating mounts doesn't appeal then the alternative is to use a flat metal mounting plate that fits between panels/vents. They are usualy used for mobile phone mounts but can double up as a screen mount. A quick google search turns up this:
http://buy-car-electronics.efastmall.com/ZZ23407.html
To this you'd fix your stock screen mount or something that swivels from Ram mounts:
http://www.ram-mount.com.
The latter alternative is what I'm thinking of for my Corvette.